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141.
Kaufmann F Daş G Preisinger R Schmutz M König S Gauly M 《Veterinary parasitology》2011,176(2-3):250-257
Groups of Lohmann Brown (LB) and Lohmann Selected Leghorn (LSL) hens were reared under helminth-free conditions and kept afterwards together in a free range system. Mortality rate, body weight development, laying performance and faecal egg counts (FEC) were recorded during a 12 month laying period. At the end of the laying period, 246 LSL and 197 LB hens were necropsied and worms counted following the World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines. In addition adult Heterakis gallinarum and Ascaridia galli were sexed and measured for length. Significant (P<0.01) differences were observed in mortality rates between LSL and LB animals (12.9 vs. 5.7%). LSL hens showed significantly (P<0.05) higher FEC when compared with LB hens at almost all dates of monitoring. Almost all animals became infected with at least one helminth species. The most prevalent species were H. gallinarum, Capillaria spp. and A. galli. LB hens showed a significantly (P<0.05) higher average number of adult H. gallinarum, Capillaria spp. and tapeworms when compared with LSL animals. However, number of adult A. galli was in tendency lower in these animals. In total, LB had a significantly (P<0.05) higher worm burden than LSL (192.3 vs. 94.3). The estimated heritabilities for total worm burden were 0.23 (SE±0.12) in LSL and 0.75 (SE±0.21) in LB, respectively. The number of all different helminth species were positively correlated. The sex ratio of H. gallinarum and A. galli and the average worm lengths were not significantly (P>0.05) different between the genotypes. There was no significant phenotypic correlation between body weight and worm burden in LSL, whereas it was the case in LB (r=0.17, P<0.05). Based on the estimated heritabilities it is possible to select for helminth resistance in both genotypes. 相似文献
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Axer Maximilian Martens Sven Schlicht Robert Wagner Sven 《European Journal of Forest Research》2021,140(4):947-968
European Journal of Forest Research - The potential utilisation of natural regeneration of European beech (Fagus sylvatica L.) for forest conversion has received little attention to date.... 相似文献
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Lotta Berntzon Sven Erasmie Narin Celepli Johan Eriksson Ulla Rasmussen Birgitta Bergman 《Marine drugs》2013,11(8):3091-3108
Cyanobacteria produce a range of secondary metabolites, one being the neurotoxic non-protein amino acid β-N-methylamino-L-alanine (BMAA), proposed to be a causative agent of human neurodegeneration. As for most cyanotoxins, the function of BMAA in cyanobacteria is unknown. Here, we examined the effects of BMAA on the physiology of the filamentous nitrogen-fixing cyanobacterium Nostoc sp. PCC 7120. Our data show that exogenously applied BMAA rapidly inhibits nitrogenase activity (acetylene reduction assay), even at micromolar concentrations, and that the inhibition was considerably more severe than that induced by combined nitrogen sources and most other amino acids. BMAA also caused growth arrest and massive cellular glycogen accumulation, as observed by electron microscopy. With nitrogen fixation being a process highly sensitive to oxygen species we propose that the BMAA effects found here may be related to the production of reactive oxygen species, as reported for other organisms. 相似文献
146.
Sven Wagner Catherine Collet Palle Madsen Tohru Nakashizuka Ralph D. Nyland Khosro Sagheb-Talebi 《Forest Ecology and Management》2010
This review describes key regeneration characteristics of the genus Fagus as represented by its four most prominent species: F. crenata (F.c.), F. grandifolia (F.g.), F. orientalis (F.o.) and F. sylvatica (F.s.). Similarities and differences in the relevant life phases of these species are identified. Those are related to natural disturbance regimes and synecological peculiarities of the forests where they grow, thereby establishing a basis for evaluating the likely outcome of different silvicultural measures. 相似文献
147.
In this study, salt‐induced changes in the growth rate of maize (Zea mays L.) were investigated during the first phase of salt stress. Leaf growth was reduced in the presence of 100 mM NaCl, and effects were more pronounced for the salt‐sensitive cv. Pioneer 3906 in comparison to the hybrid SR03. While hydrolytic activity of plasma membrane remained unaffected, H+‐pumping activity was reduced by 47% in Pioneer 3906, but was unchanged in SR03. Changes in apoplastic pH were detected by ratiometric fluorescence microscopy using the fluorescent dye fluorescein isothiocyanate‐dextran (50 mM). Pioneer 3906 responded with an increase of 0.2 pH units in contrast to SR03 for which no apoplastic alkalization was found. With respect to the hypothesis that the apoplastic pH is influenced by salinity, it is suggested that salt resistance is partly achieved due to efficient H+‐ATPase proton pumping, which results in cell‐wall acidification and loosening. 相似文献
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Klemens Ekschmitt Ellen Kandeler Christian Poll Andreas Brune Francois Buscot Michael Friedrich Gerd Gleixner Anton Hartmann Matthias Kstner Sven Marhan Anja Miltner Stefan Scheu Volkmar Wolters 《植物养料与土壤学杂志》2008,171(1):27-35
We review recent experimental results on the role of soil biota in stabilizing or destabilizing soil organic matter (SOM). Specifically, we analyze how the differential substrate utilization of the various decomposer organisms contributes to a decorrelation of chemical stability, residence time, and carbon (C) age of organic substrates. Along soil depth profiles, a mismatch of C allocation and abundance of decomposer organisms is consistently observed, revealing that a relevant proportion of soil C is not subjected to efficient decomposition. Results from recent field and laboratory experiments suggest that (1) bacterial utilization of labile carbon compounds is limited by short‐distance transport processes and, therefore, can take place deep in the soil under conditions of effective local diffusion or convection. In contrast, (2) fungal utilization of phenolic substrates, including lignin, appears to be restricted to the upper soil layer due to the requirement for oxygen of the enzymatic reaction involved. (3) Carbon of any age is utilized by soil microorganisms, and microbial C is recycled in the microbial food web. Due to stoichiometric requirements of their metabolism, (4) soil animals tend to reduce the C concentration of SOM disproportionally, until it reaches a threshold level. The reviewed investigations provide new and quantitative evidence that different soil C pools underlie divergent biological constraints of decomposition. The specialization of decomposers towards different substrates and microhabitats leads to a relatively longer persistence of virtually all kinds of organic substrates in the nonpreferred soil spaces. We therefore propose to direct future research explicitly towards such biologically nonpreferred areas where decomposition rates are slow, or where decomposition is frequently interrupted, in order to assess the potential for long‐term preservation of C in the soil. 相似文献